If the posts aren't linked (shared comments/faves) then I would suggest that everyone gets a private tab in their galleries/user page/whatever that is something along the lines of "Submissions you're involved in" that displays the posts that they are connected to and/or mentioned in. This helps artists to keep track of their art posted by commissioners, helps people involved in a piece to view the responses to it when it's posted on other peoples' galleries, etc.
If the posts aren't linked (shared comments/faves) then I would suggest that everyone gets a private tab in their galleries/user page/whatever that is something along the lines of "Submissions you're involved in" that displays the posts that they are connected to and/or mentioned in. This helps artists to keep track of their art posted by commissioners, helps people involved in a piece to view the responses to it when it's posted on other peoples' galleries, etc.